Buildings that house electronic telecommunications equipment may be segmented into a number of rooms. In the case of mobile switching centers (MSCs), or similar facilities, one or more rooms may house various servers, routers, switches, and other telecommunications equipment, and another set of rooms may house computers that control operation of such equipment. Many advantages are provided by maintaining certain electronic equipment in separate rooms, including configuration of the indoor environment (e.g., temperature and humidity) for reliable operation of specific types of equipment, efficiency of operation and ease of interconnectivity of related equipment in close proximity.
Electronic equipment spread across various rooms of an MSC may be interconnected through communications cabling, or fiber, that extends through fiber ducts formed in the walls separating the rooms. These fiber ducts present problems when planning a fire suppression scheme for a multi-room facility. A given facility will typically have a fire suppression system specifically designed to put out the types of fires that are commonly encountered, such as electrical fires. Traditional fire suppression systems utilized where electronic equipment is present accomplish their intended function by either (a) absorbing a large amount of heat energy present in a room to reduce the surface temperature of burning material below it's ignition point, or (b) reducing the oxygen level in a room to a level that is too low for combustion to occur. For instance, fire suppression systems that work on the principle of heat energy absorption may employ various gasses and aerosols, such as potassium compounds suspended in carrier gasses, that are discharged into a particular room when a fire is detected. A similar principal may be applied in systems that reduce room oxygen levels, such as by the discharge of gasses containing a high concentration of carbon dioxide. In either case, the effectiveness of the fire suppression system depends on the ability to maintain the discharged gasses within a room of a given volume until the fire has been eliminated. Unfortunately, fiber ducting provides a path by which the discharged gasses can leave a room, reducing the effectiveness of fire suppression. This is because the cabling does not completely fill the space at the entrance and exit regions of the duct. The fiber ducting may also provide a direct path by which a fire may travel between rooms.
Efforts to fill in the open space around cabling within a duct have led to the use a fire barrier “pillows” or “blocks”. These blocks are formed of materials that have a high ignition temperature to resist being consumed by a fire, as well as with intumescent properties so that the blocks expand to fill an open space when exposed to the extreme heat of a fire. Once cabling is extended through a duct, the blocks are placed in the opening of the duct around the cabling.
Fire barrier blocks are effective in blocking the escape of fire suppression system gasses to some degree, but an airtight seal remains difficult within a duct due to imprecision of fitting one or more blocks around cabling and cable trays or within cable-carrying conduits of varying geometries. It is also labor intensive for an installer to cut the blocks on site in order to achieve an improved geometry within the duct for a tighter fit around the cabling.